A method by which a terminal receives data in a wireless communication system and a device using the method are provided. The method is characterized by receiving first data in a unit of transport block, the transport block including at least one code block, transmitting acknowledgement/negative-acknowledgement (ACK/NACK) information for each code block, of which there is at least one, and receiving, in a unit of code block, second data included in a code block, for which NACK has been transmitted, among code blocks, of which there is at least one.